Restoring cwm backups of a different rom topic

This was something i tried to do, resulting in a soft brick, which i only got out of by flashing stock with odin and reflashing my rom.
basically, i flashed cyanogenmod, and made a cwm backup, but kept my stock cwm backup. i thought that by restoring either backup, i could "dual boot" my phone.
it didnt work. the phone went crazy, and soft bricked. im guessing that it has to do with the partitions, since cm10 and stock have different partitions.
if anyone knows what really went wrong, let me know please.